This invention relates to metal treatment. In particular, this invention relates to a method for reducing carbonaceous residues on metals processed at high temperatures.
Prior to high-temperature exposure, metals are typically treated with various compositions. For example, rolling oil compositions are employed in the cold reduction of steel, and the steel is only partially cleaned of this oil with mill detergent compositions prior to annealing. Since the mill detergent also typically functions to deposit a rust-preventive film to protect the steel during storage, the mill detergent also is not removed from the steel prior to annealing, and the presence of the carbonaceous residue comprising the thermal decomposition products of the oil and detergent on the steel after anneal interferes with subsequent processing. It is thus highly desirable to reduce such carbonaceous residues to provide the cleanest possible steel surface for post-anneal processing of the steel.
It is accordingly an object of the invention to provide a method for reducing the carbonaceous thermal decomposition product residue of metal-treating compositions on treated metal processed at high temperatures.
It is also an object of the invention to provide a method for reducing the thermal decomposition product residue of rolling oil and mill detergent on annealed steel.
It is an additional object of the invention to provide a method for improving adherence of finish or prefinish coatings, such as phosphate coatings, to steel treated with oil or detergent and subsequently annealed.
It is another object of the invention to provide a method for improving the corrosion-resistance of steel by reducing the carbonaceous residue of steel-treating compositions on the surface of annealed steel, thereby facilitating application of preservative coatings.
It is a further object of the invention to provide a method for improving the clean-burning characteristics of metal-treating compositions to substantially reduce the non-volatile carbonaceous thermal decomposition products thereof.